Sedation and Anesthesia of Galapagos (Chelonoidis nigra), Aldabra (Aldabrachelys gigantea), and African Spurred Tortoises (Centrochelys sulcata): A Retrospective Review (2009–2019)

SIMPLE SUMMARY: Anesthesia is often required for the medical management of large tortoise species, but little has been published regarding effective anesthetic regimens for these species. The purpose of this study was to review anesthetic regimens that have been used safely and effectively in Galapagos (Chelonoidis nigra), Aldabra (Aldabrachelys gigantea), and African spurred (Centrochelys sulcata) tortoises, with the aim of improving medical management. ABSTRACT: Tortoises belong to the taxonomic family Testudinidae, which is considered one of the most imperiled families of the order Testudines. Anesthesia is often required for the medical and surgical management of large tortoises. The objectives of this retrospective study were to review drug regimens used to successfully anesthetize Galapagos (Chelonoidis nigra), Aldabra (Aldabrachelys gigantea) and African spurred (Centrochelys sulcata) tortoises, and to compare the times to effect and to extubation in tortoises administered different premedication protocols. Anesthetic records of giant tortoises admitted to the University of Florida College of Veterinary Medicine between January 2009 and December 2019 were reviewed. A total of 34 tortoises (six Aldabra, 23 Galapagos, and five African spurred) were included, resulting in 64 anesthetic events. Frequently used premedication protocols included an α(2)-adrenergic agonist and ketamine combined with either midazolam (group α(2)−adrenergic agonist, midazolam, ketamine, AMK; n = 34), a μ-opioid receptor agonist (group α(2)−adrenergic agonist, μ-opioid receptor agonist, ketamine, AOK; n = 13), or a μ−opioid receptor agonist and midazolam (group α(2)−adrenergic agonist, midazolam, μ-opioid receptor agonist, ketamine, AMOK; n = 10). Inhalant anesthetics (isoflurane, n = 21; sevoflurane, n = 23) were frequently used for maintenance of anesthesia following premedication. Out of the 34 total tortoises, 22 had only one anesthetic event, five had two anesthetic events, three had three anesthetic events, and four had four or more anesthetic events. Few adverse effects were observed and there was no mortality reported during the peri-anesthetic period. Sedation and general anesthesia of giant tortoises can be successfully performed with a combination of an α(2)-adrenergic agonist and ketamine in combination with midazolam and/or a μ−opioid receptor agonist.